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Vascular plants from Odzala National Park: Commented list of species new for Congo-Brazzaville
Abstract
A list of 84 vascular plant species, collected in the Odzala National Park (Rép. Pop. Congo - Congo-Brazzaville), not mentioned in Sita & Moutsamboté's Catalogue of Plants from Congo-Brazzaville (1988) is given. Distribution maps and comments are provided for the most interesting species. A short phytogeographical outline of the region is also given. A new combination, Solenostemon giorgii (De Wild.) Champl. (Labiatae), is made and this species is lectotypified.
... In RoC, there is a published inventory for the vascular flora of the Republic of Congo (Sita and Moutsambote (1988)), which provides a list of 4397 species (198 families and 1338 genera), but with the vast majority being forest species and no indication of their distribution. This inventory has been slightly updated since then, with 84 species added by Champluvier and Dowsett-Lemaire (1999), and 64 by Lachenaud (2009). More usefully, there is an illustrated list of plants of the Lesio Louna and Lefini reserves, which are major reserves covering 6% of the Bateke Plateau, that list 457 species belonging to 119 families (Nsongola et al. 2006). ...
The Bateke Plateau in the Republic of Congo is one of the last frontiers for ecology, with little known about its floristics and physiognomy. Despite occupying 89,800 km² and its importance for local livelihoods, its ecology and ecosystem functions are poorly understood. Situated on Kalahari sands, the Bateke has a complex evolutionary history, mainly isolated from other savannas for much of its past, with currently unresolved ecological implications. Here, we assess the biomass and floristic diversity of this savanna. We established four 25-ha permanent sample plots at two savanna sites; inventoried all trees; assessed biomass and species composition of shrubs, forbs and grasses; and characterized the soils. Total plant carbon stocks (aboveground and belowground) were only 6.5 ± 0.3 MgC/ha, despite precipitation of 1600 mm/yr. Over half the biomass was grass, with the remainder divided between trees and shrubs. The carbon stock of the system is mostly contained in the top layer of the soil (16.7 ± 0.9 MgC/ha in 0–20 cm depth). We identified 49 plant species (4 trees, 13 shrubs, 4 sedges, 17 forbs, and 11 grass species), with an average species richness of 23 per plot. There is tree hyperdominance of Hymenocardia acida (Phyllanthaceae) and a richer herbaceous species composition dominated by Loudetia simplex and Hyparrhenia diplandra. The low carbon stocks and tree biodiversity, compared to other African savannas, are surprising considering the high rainfall. We speculate it is due to low nutrient soils, high fire frequency, and the effect of a temporally variable and restricted connection to the main southern African savanna complex. © 2018 The Authors. Biotropica published by Wiley Periodicals, Inc. on behalf of Association for Tropical Biology and Conservation
This work is the first analysis of the totality of the plant biodiversity inventories made in the Odzala National Park. It deals especially with habitat diversity and phytogeographical groups based ou the correctly determined species of the curent flora. The global taxonomic list consists of 1141 species belonging to 125 families. Forest habitat is the most diversified with 806 species reaching 71% of the total, of wich 537 belong to the "forêt de terre ferme". Grassy habitat includes 335 species reaching 29% of the total, 143 species belonging to the savanna. At the phytogeographical groups level, the basic Guineo-Congolian element is the most important with 666 species (58% of the flora). Species with very broad geographical area follow with 271 species (24% of the flora). Correlation between habitat and phytogeographical groups has been established. The predominance of the basic Guineo-Congolian element in forest sites where the human influence is lesser displays the stability of these habitats. The importance of species with very broad geographical area in grassy habitats illustrates the secondary or substitution character of these sites, mainly created by human activities.
A new species of Sorindeia, S. ripicola, is described from Congo-Kinshasa. It was hitherto confused with Sorindeia sparanoi. The differences between the two species and their distribution maps are given. The new species' distribution and ecology is compared to that of Bridelia ripicola and other Euphorbiaceae.
The global taxonomic list of the Odzala national Park consists 238 species belonging to 47 families. Comparison of the transects floristical composition has allowed us to point out three forests clusters, confirmed by the DCA (Detrended Correspondence Analysis) of dense forests relevés: - western forests, where diversity is higher and constituted by the Plagiostyles africana and Coelocaryon preussii plant community; - central-south forests, groups dominated by the Pausinystalia macroceras and Dialium pachyphyllum community; the north eastern forests, where species diversity index are lower and characterized by Keayodendron bridelioides and Markhamia tomentosa. At the families level, the diversity of the Mimosaceae, Burseraceae and Myristicaceae changes according to the gradient southwest/northeast, characterized with a conspicuous species impoverishment.
Aim – This paper aims to provide the first exhaustive list of woody species present in the northern part
of the Republic of Congo, describing the vegetation types, characterizing the ligneous forest stands and
explaining the distribution range of characteristic species.
Location – The 1.23 million ha of the logging concession of ‘Congolaise Industrielle des Bois’, situated in
the North of the Republic of Congo (1.41°N 16.32°E), were prospected during six years. The study area is
bordered by the Sangha River to the west and by the Likwala-aux-Herbes swamps to the east.
Methods – The checklist, given as an electronic appendix, documents 702 woody species. Each species is
annotated with the following headings when the information is known: scientific, pilot and local names, lifeform,
preferential habitat, distribution, seed dispersal type, human use, abundance and foliage phenology.
Field observations have been augmented with existing bibliography.
Results – A total of 392 genera and 79 families are presented. Ficus is the largest genus with seventeen
species. 73% of taxa are endemic to the Guineo-Congolian Region centre. The sarcochorous functional
diaspore type represents 71%. Eleven percent of the species are anemochorous and are mostly emergent
trees. Forty-four species newly recorded for the Republic of Congo are especially commented.
Main conclusions – Terra firma forests are characterized by deciduous, light-demanding and winddispersed
emergent tree species. Evergreen stands are mainly found at the confluence of the Sangha River
and Likwala-aux-Herbes swamps. This forest could be regarded as equivalent to the other interfluvial forest
blocks of the Major Fluvial Refuge in the Congo basin.
Sixty-four species are newly reported from the Republic of Congo. The occurrence of seven species reported without specimen citation by Sita & Moutsamboté (1988), and which constitute important range extensions, is also confirmed and documented. The vascular flora of the Republic of Congo now includes about 4538 species, fifteen of which are endemic. Its diversity nearly compares with that of neighbouring Gabon (4710 species), which, however, has a much higher number of endemics (508 species).
French
Soixante-quatre espèces sont signalées pour la première fois de la République du Congo. La présence de sept espèces signalées sans indication d'échantillons par Sita & Moutsamboté (1988) et qui constituent d'importantes extensions de répartition, est également confirmée et documentée. La flore vasculaire de la République du Congo comporte environ 4538 espèces, dont quinze endémiques. Sa diversité est donc presque comparable à celle du Gabon voisin (4710 espèces), où le nombre d'endémiques est cependant beaucoup plus élevé (508 espèces).
A new species of Sorindeia, S. ripicola, is described from Congo-Kinshasa. It was hitherto confused with Sorindeia sparanoi. The differences between the two species and their distribution maps are given. The new species' distribution and ecology is compared to that of Bridelia ripicola and other Euphorbiaceae.
The African genus Keetia E. P. Phillips is reinstated; species from countries included in the Flora of Tropical East Africa and Flora Zambesiaca are revised and the remainder discussed; 22 new combinations are made (19 specific and 3 infraspecific); 7 new species are described, new synonyms are indicated and distributions given.
A taxonomic revision of the Irvingiaceae is presented. Three genera Desbordesia (1 species), Klainedoxa (2 species) and Irvingia (6 species) are recognised. Standard herbarium characters are not very useful in the identification of the species of Irvingia. Additional field characters and in particular fruit characters facilitate identification.